A study is being made of chemically- or electrically-induced seizure activity in mouse brain. Work to date has indicated that elevated cyclic GMP concentrations in the cerebellum are assoicated with many types of seizures, and that when convulsions are suppressed by drugs, cyclic GMP is decreased. In addition, increased GABA concentrations may be involved in anticonvulsant action. Studies on whole mouse brain indicate that a major locus of action of phenytoin is in the cerebellum. Microdissection and microanalytical procedures are being used to analyze cerebellar layers after electroshock and in the presence of phenytoin. BIBLIOGRAPHIC REFERENCE: Lust, W.D., Kupferburg, H.J., Passonneau, J.V. and Penry, J.K.: On the mechanism of action of sodium valproate: The relationship of GABA and cyclic GMP in anticonvulsant activity. In Legg, N.J. (ed.): Clinical and Pharmacological Aspect of Sodium Valproate (Epilim) in the Treatment of Epilepsy. Tunbridge Wells, England: MCS Consultants, 1976, pp. 123-129.